Pump



July 11, 1961 H, L, FOSTER 2,991,721

PUMP

Filed Oct. '7, 1957 5 Sheets-Sheet 1 `uly 11, 1961 H, L, FOSTER 2,991,721

PUMP

Filed Oct. 7, 1957 5 Sheets-Sheet 2 July 11, 1961 H. L. FOSTER 2,991,721

PUMP

Filed oct. 7, 1957 5 sheets-sheet s /Q/,/f F05 fer INVENTOR.

July 11, 1961 H, L FQSTER 2,991,721

PUMP

Filed oct. 7, 1957 5 sheets-sheet 4 H. L. FOSTER July 11, 1961 PUMP 5 Sheets-Sheet 5 Filed Oct. 7, 1957 United States Patent O 2,991,721 PUMP Hubert L. Foster, 2602 Cr'ocker, Houston, Tex. Filed Oct. 7, 1957, Ser. No. 688,539 6 Claims. (Cl. 103-4) This invention relates to new and usefulimprovements in a pump.

It is an object of this invention to provide a pump :for increasing the flow of a well by compression of gas and aeration of the production and of the power uid employed.

It is another object of Ithe invention to provide a double acting pump, in cooperation with a multiple stage double acting gas compressor driven by a iiuid motor for use in single or dual formation wells.

It is another object of `the invention to provide a pump operated by static uid pressure or by static lluid pressure with a minimum of pressure froml additional' sources in cooperation with the static fluid pressure.

It is still another object of the invention to provide a pump for single or dual formation wells driven by a uid motor in which the uid furnishing the motivating power is maintained separate and apart from the production ow and provides a clean lubricating power uid for continuous, cool pump operation and gas compression regardless of whether or not the ow of production is continuous and steady.

It is still another object of the invention to provide a pump for production Afrom various strata levels simultaneously, the ilow of each strata being through individual tubing but aerated by the common flow of gaseous uid.

It is still a further object of the invention to provide a pump of novel design that may be quickly and easily removed from the well for repair or servicing purposes.

With the above and other objects in view, the invention has relation to centain novel features of construction, operation and arrangement of parts more particularly dened in the following speciiication and illustrated in the accompanying drawings, wherein:

FIGURE 1A is a cross sectional elevational view of a portion of the pump, illustrating the upper portion of the pump mechanism.

FIGURE 1B is a sectional view, in elevation, and in continuation ofthe view shown in FIGURE 1A.

FIGURE 1C is a cross sectional elevational View of the pump in continuation of the view shown in 1B.

FIGURE 1D is a cross sectional elevational view of the pump in continuation of the View shownv in FIG- URE 1C.

FIGURE 1E is a cross sectional view of the pump inV continuation of the view shown in FIGURE 1D.

FIGURE 2 is a cross sectional upper end view of the pump.

FIGURE 3 is a cross sectional View taken on the line 3 3 of FIGURE lA.

FIGURE 4 is a cross sectional end view taken on the line 4 4 of FIGURE l.

FIGURE 5 is a cross sectional end view taken on the line 5-5 of FIGURE 1C, and

FIGURE 6 is a cross sectional end view taken on the line 6-6 of FIGURE 1D.

FIGURE 7 is an enlarged elevational view, in cross section, illust-rating Ithe main sliding valve in one position, and

FIGURE 8 is an enlarged elevational view, in cross section, of the main sliding valve shown in another position.

Referring now more particularly to the drawings, the numeral 1 designates a well casing. The pump is enice closed in a jacket, forming the pump insert the upper end of the jacket 2 being secured to the lower end of a string of tubing 3 by means of an adapter collar 4. 'Ihe jacket 2 extending downwardly from the lower end of the collar 4. A J-tool 6 suitably mounted on the lower end of the production tubing 11 cooperates with a suitable pin 7 in the swab mandrel 8 to lock the tubing 1-1 to the mandrel 8. Suitable swab cups as 9, 10 are mounted on the mandrel 8. 'Ihe production tubing 11 extends downwardly through the end of the tubing 3 and concentric with the tubing 3, forming the upper production cylinder 12. A suitable collar 13 anchors the tubing 11 to the seal 78 adjacent the mandrel 8. Dhe annulus between the tubings 11 and 5 create the passageway for the lower production from the lower production pump discharge outlet 79, and the annulus between the tubing 5 and 2 is the area for the passage of the product-ion `from the upper formation through the pont 80 and check valve 81.

The pump is composed off two separate sections. r["he outer section consists of a double walled annular case Iformed by the members 2', 35. All of the tubular passageways, or conduits, that communicate with the various pants of the inner section are mounted on the member 35 between the wallsformed by the members 2', 35. The louter case also acts as a heat exchanger, having the usual production uids surrounding the conduits and acting as a cooling agency. By mounting the conduits in a separate section, the power, production and compressor cylinders of the insert pump forming the inner section may be yof a greater diameter than is possible withthe type of insert pump presently known tothe art for a specitied size of tubing. The outer case may be lowered into the well as a part of the tubing string and the tubing and casing can be cleaned by circulating cleaning fluid through the tubing and out through the casing-outer case annulus before the inner section is installed. As there are no parts to wear in the annular outer case section, it does not have to be removed from the well ttor repairs or servicing. The insert section consists of the flu-id motor which is positioned in the axial center of the unit and which is hereinafter more particularly described. Attached to each end -ot the uid motor is a multiple stage gas compressor and a [production uid insert type pump hereinaiiter more panticularly described. At the top and bottom of the insert type pump are attached conventional swab cups as 9, 10, 72. The swab cups hold the insert section in the longitudinal center of the tubing to keep the various seals from being damaged upon installation and to clean the tubing as the insert section is lowered or and the insert section to form the complete pumping unit.

Neither section will operate without the other, as the cylinders are in the inner section and the conduits are in the outer section. The lower end of the double walled outer case will be connected to a conventional casing packer as 95, sealing the production zone trom the casing annulus. A conventional gas-oil separator, as 96, is connected to the lower end of the outer case and extends into the production area below the packing element 95. The gas intake conduits 17 lare connected to the annular space outside of the gas separator just below the packer 95. The production uid conduits may be connected to the area beneath the outer case. The separator as 96 extends through the lower well bore at least several feet to form a uid seal between the well gas and well iluid.

Power oil pressure line 1S extends vertically in the well casing and is fastened to the outside of the tubing 3 yfor support, and terminates in a collar from which four separate power oil pressure lines `as 15 extend to the various ports hereinafter referred to. The power oil exhaust line 16 also extends vertically in the casing and is anchored to the tubing 3 for support and terminates in a collar vfrom which four separate power oil exhaust lines as 16' extend to the various power oil exhaust ports hereinafter referred to. A first stage gas vent line as 17 extends vertically in the casing 1 yand is anchored to the tubing 3 for support. The gas injection line 17 terminates in a collar from which there are four separate gas injection lines 17 which extend to the various gas intake ports hereinafter referred to. A by-pass collar 20 anchors all of the above mentioned lines, receiving them in suitable ttings in its lower end face for continuation of said lines. This collar 2G acts as `a terminal -for all of said lines, vand is externally and internally threaded so that it may be anchored to the tubing 2 and 5 and the outer case 2.', 35.

An adapter coupling 21 secures the swab mandrel 8 to a valve case 22 which houses the intake valve 23 which has a discharge port 24 and the exhaust valve 25 having a discharge port 26 into and through the jet nozzle 85 for the upper formation pump discharge. The intake valve is spring loaded as at 27 to prevent accidental unseating by, gravity. The gas exhaust ports 86, 86 direct a flow of gaseous uid from the last stagev of the compressor under pressure into the production exhaust ot the upper fluid pump into the tubing 11 through the mandrel 8, mixing with the production iluid from the valve 25 of the pump cylinder 35.

An upper pump cylinder 36 is internally threaded at its upper end and mounted on said upper end of said pump cylinder 36 is the lower end of the valve casing 22. A piston 82 reciprocates in the cylinder 36 and this forms the upper pump production cylinder area. The piston 82 is -a double acting piston, having heads on each end, and the area 23 below the piston 82 Iforms the second stage gas compression chamber for the upper gas compressor. A piston rod 29 is secured at the upper end to the piston 82 and connects at its other end to the power piston 30. The power piston 30 is the first stage compressor piston for the upper gas compression cylinder 31 and is the power piston for power cylinder 44 `and is mounted on the lower end of the rod 29a. 'Ihe rod 29a coupled to the rod 29 by self aligning nuts 89 and a spring loaded hydraulic pilot valve 32 is mounted on the piston 30 around the upper end of the rod 29a` This pilot valve is free to move in either direction and travels with the pis-ton rod 29a to the full end `of the stroke. The spring 33 urges the valve towards a neutral position and the bumper spring 34 absorbs the shock on the pilot valve at the end of the stroke and maintains the valve in a neutral position during the stroke.

The power oil pressure and power oil exhaust columns are lacting on the balanced pistons such as pistons 30, 30a and the exposed area of the valve 53 and bushing 54 and these are exposed to the same static pressure, when the pump is not operating. When the power oil pressure, from the surface, is turned on, the dierential in pressure reacts as useable force on the power piston 30a and the exposed area of the valve 53 to start the uid motor reciprocating. As more particularly illustrated in FIGURE 7, as power oil pressure is 4applied through the ports 57, 57 into the power cylinder 46, the pressure is against the annular valve 53 and bushing 54, holding the valve in the up position. Also the pressure is against the power piston 30a forcing it downwardly; as the rod 29a strikes power piston 30a on its lower end and power piston 30 on its upper end, they reciprocate together. As the rod 29a and pistons 30, '30a move downwardly, the upper power cylinder 44 is exhausting through the exhaust ports 52, 52. The differential in pressure on the lower end of the annular valve 53 and bushing 54 hold the valve 53 in its upward position during the downward stroke. The area of the valve 53 exposed to the difference in pressure is approximately one and one half square inches, the differential power oil pressure at the pump setting, which should be ap- 4 proxmately three thousand pounds per square inch for ten thousand feet. Therefore, the force holding the valve 53 seated in the up position is approximately four thousand live hundred pounds. It is apparent the valve 53 will not move out of its seated position during the downard stroke. Also it lis apparent that to move the valve to the opposite position, a greater hydraulic force is needed. Therefore, when the hydraulic pilot valve 32 rests on the seat at the upper end of the annular valve 53, the power oil exhaust in the power cylinder 44 below the power piston 30 reacts hydraulically on the pilot valve 32 against the annular valve 53 to overcome the force holding the valve 53 seated in its upward position. As this exhaust power oil is at static pressure, it must act on an area larger than the area holding the valve 53. As the pressure ports S7, 57 are open until the valve 53 is seated in its downward position, the power the power cylinder 30 above the pilot valve 33 is sutlipiston 30a continues downwardly until the pressure in cient to unseat the valve 53. When the valve 53 is opened the least bit, power oil pressure enters through the pressure ports 51, 51 and the power oil pressure is immediately equalized in both power cylinders 44 and 46. This causes the rod 29a and piston 30 and 30a to stop, but the pilot valve 32 continues to move the valve 53 hydraulically to its opposite position.

A jacket 35 incloses the upper production cylinder 36 and is secured to the valve housing 22.

Between the upper cylinder 36 and the piston compressor cylinder 31 is the valve housing 37 in which the intake valve 38, and exhaust valve 39 are housed, and

which serve the gas compressor chamber 31, and the intake valve 40 and exhaust valve 41 serve the gas compressor chamber 28.

A bushing 42 is snugly tted around the piston rod 29 to form a seal between the cylinders 28 and l31 and is maintained in place in the valve housing 37 around the piston rod 29 by means of the snap ring 43, and the enlarged shoulder at the bottom of the bushing.

Beneath the valve pilot 32 is the upper power cylinder 44 and depending from this cylinder is the main annular sliding valve case 45 which is connected at its lower end to the lower power cylinder 46. Sleeves 47, 48 are secured to the main sliding valve 53 by means of snap rings as 49, 50. The sleeve 47 forms a seal between the power oil intake ports as 51, 51, and the power oil exhaust ports 52, 52, and the sleeve 48 forms a seal between the oil intake ports as 57, 57 and exhaust ports as 58, 58.

The hydraulically operated main sl-iding valve 53 as shown in FIGURES 7 and 8 is mounted on the sliding valve bushing 54 which is slidably mounted on the rod 29a and which seals off the power cylinders 44 and 46. The differential in pressure on the exposed area of the opposite ends of the main sliding valve, hydraulically causes Ithe valve 53 to remain seated during the reciprocation of the rod 29a. The valve 53 `has a pair of exhaust seats 55, 56 which are spring loaded as the spring 55a to constantly urge the exhaust seats apart and into the desired position and power oil exhaust pressure enters through the port 61 to bear against these seats 55 and S6 to assure their movement to full position and their being retained in such position against gravity. As the pilot valve 32 moves downwardly with the rod 29a and seats on the upper end of the main sliding valve 53, the exposed area of the valve 53 is unbalanced in favor of the direction of movement of the stroke, the exhaust of power oil through the area between the upper end of the sliding valve and the piston rod 29a gradually is blocked and the entrance of power oil through the ports 51, 51 is gradually commenced; as the movement downward continues, the entrance of power oil through the ports 57, 57 gradually is blocked and the power oil entering `the ports 51, and 57, produces a balance of pressure in the cylinders 44, 46, the rod 29a stops, but the pilot valve 32 continues to move the main sliding valve hydraulically to its alternate position. The inlet of power oil through the ports 51 flowing around the upper end of the valve 32 in the cylinder 44 and into the area behind the valve 32, until stopped by the seal 87, will continue hydraulic pressure Iagainst the main sliding v-alve 53 until the ports 57 are entirely closed and the ports 51 entirely opened, and the exhaust ports 52 entirely closed and the exhaust ports 58 entirely opened, and the opposing end of the main sliding valve 53 is seated on the seat 88 of the opposite end of the valve case 45, and the power oil entering through the ports 51 and bearing against the piston 30 reverses the stroke of the rod 29a.

The rod 29a is coupled at its lower end to the rod @9b by self-aligning nuts 90 and the piston 30a is mounted on thelower end of the rod 29a and the valve 59 is mounted on the piston 30a `and around the lower end of the piston rod 29a, said piston and valve being operated in exactly the same manner as the piston and valve above described. As the piston 30a reaches the end of its stroke Iancl the valve 59 seats on the opposing end of the main sliding valve 53, the hydraulic pressure against the pilot valve 59 causes a continuation of movement of the main annular valve 53 to again change the position of the main annular valve 53 and reverse the flow of power oil and to reverse the direction of movement of the rod 29a.

Suitable check valves as 60, 61 permit compressed gaseous uid to pass from the Arst stage gaseous fluid cylinder 62 into the second stage gaseous uid cylinder 63. Said valves 60, 61 opening upon pressure in the cylinder 62 and permitting the flow into the cylinder 63 and closing upon back pressure in the cylinder 63, preventing a return of the gas into cylinder 62. Gaseous iluid enters the cylinder 63 through the valve 64 and exhausts from the cylinder 63 through the valve 65. The piston 66 forms the second stage compression and lower pump piston and an inlet valve 67 admits production fluid into the lower production cylinder 68 and exhausts production iluid from the lower production pump cylinder 68 into the lower exhaust valve 69 and from the valve 69 through the exhaust port 91 into the lower production fluid exhaust lines as 92, the lines 92 terminating in the collar 20 and the iiow continues through the annulus between the tubing 5 and 11 to the ground surface.

An adapter collar 70 secures the lower swab mandrel 71 to the lower valve casing 22, and suitable swabs as 72, 72 are secured to the lower mandrel 71. A line up cap 73 is mounted on the lower end of the mandrel 71 and a slot 74 therein receives the line-up pin 75 mounted in the plug 76. A suitable standing valve as 77 is secured to the lower end of the annular case 2, 35 through which production may -flow into the production annulus.

All of the lines such as a, l16a, terminate at the lower end of the annular case 2, 35 Vand are suitably capped or plugged at that point as by the plugs 83.

A gas inlet 93 is provided through the standing valve housing 94 having a suitable back pressure valve to permit the ow of gas from the lower formation into the gas vent lines 17. As long as gas pressure is available, this gas supply provides gas for the rst stage compressors. This may be controlled by the use of a gas regulator (not shown) -at the ground surface connected to the gas vent line 17.

The upper and lower gas multiple stage compressors 28, 31 and 62, 63, generate considerable heat during operation and require -a cooling agency. The well production uid surrounding the plurality of outlet lines gas compressor 17b in the annular case 2, 35 surrounding these compressors act as a cooling agency for the compressors. The production oil flows aroundthe gas compressor outlet tubes 17b which all carry hot gases and the production iluid is thus heated prior to entrance into the production cylinders, and as it passes upwardly through the double walled annular case, it is further heated by the gas outlet tubes 17b, and when the production iuid enters the annulus between tubings 5 and ill, it will be relatively hot. At this point, it mixes with gas from vthe compressors at approximately the same heat as the gas, and is thus aerated all of the way to the ground surface. This heated gas will similarly heat the power oil exhaust as it passes upwardly through the annular case 2, 35. This applies to the upper production from the upper formation as it passes downwardly through the annular case 2, 35 around the exhaust gas and the lower pump production lines 9a. This production blends with the hot gas as it passes through the injection nozzle 85 and the gas enters through the ports 86.

The pump double wall annular case and insert pump may be lowered into position in a well casing as a unit or by lowering the annular case 2, 35 in position and then lowering the swab mandrels which are coupled to the tubing 11 by the J-tool 6, with the pump section, into the annular case as an insert. The line-up cap 7-3 will move the pump so that the ports will be in alignment with the respective lines and passageways as the lower swab mandrel seats itself in the bottom of the double wall annular case.

In the event it is desired to utilize this invention in a single formation well, the tubing 11 and the J-tool 6 are omitted. 'I'he opening through the valve 81 for the upper formation production is plugged and the extended lines through the annular case 2, 35 serving the upper pump `are opened at the bottom of the annular case so that the production through the standing valve may pass to the upper pump. In installing a single formation pump, the main tubing and annular case may be lowered rst as part of the tubing string. After the annular case is in the desired position, in the well, the

insert pump and mandrels may be inserted `at the top of the tubing 5 at the ground surface and lowered to seat in the double wall annular case at the bottom of the well by any suitable means. The static pressure in the tubing 5 will force the insert pump to remain seated at its proper setting where it will be aligned by the lineup pin 75, to place the lines., passageways and ports in proper relation. The power oil pressure line from the surface connection used as motive power is connected to the proper connections for the power oil supply and the tubing 5 is then coupled to a proper storage facility.

The power oil enters through the line 15a into the cylinder 44 through the port -51 and moves the piston 30 and rods 29a and 29b upwardly and upon reaching its end stroke, the annular sliding valve 53 closes the port 51 and opens the port 57 and the power oil then flows against and moves the piston 30a and rods 29a and 29b downwardly in the same manner. Where there is dual production, the production from one formation such as an upper formation -ows into the cylinder 36 through the valves 23 and upon upward movement of the rod 29 and piston l82, the valve 24 closes the inflow of production fluid into cylinder 36 and the production fluid is forced out of the cylinder 36 through the valve 25 and jet nozzle into the mandrel 8 and into the production tubing 11. The power oil upon exhaust passes into the collar 20 and into the tubing 16. The gaseous fluid is vented through the lines 17a into the cylinders 62, 31 through the valves 38 and 64 and from there into the cylinders 63, 28 through the valves 39, 40 and 60, 61 and is discharged from the cylinders 63, 28 through the valves 41 and `65 into the line 18 through the ports 86 into the production line, where it mixes with the production diuid. The lower production uid enters the cylinder 68 through the valve 67 and is pumped into the production line 92 through the valve `69 and ports 91. Each compressor cylinder 28, 63 discharges the com- 7 pressed exhaust gases through its multiple discharge ports into the production passageways and into the power oil exhaust passageway `16 so that both the power oil and the production `fluids will be aerated to assist in its upward movement.

When it is desired to remove the pump, in single formation wells, the How of power oil through the power oil lines is reversed, and the power oil is pumped through the power oil exhaust lines. These exhaust lines terminate below the lower swab cups 72 as shown in FIG- URE lE `and the larea beneath the cups 72 and the bottom of the jacket will lact as a cylinder with the cups acting as a piston, to permit the pump to be unseated upwardly out of the annular case by hydraulic pressure and by the use of any desired means, the pump may be raised to the ground surface.

When the pump is used in wells having become exhausted or depleted, then the multiple stage gas compressor becomes a vacuum pump, creating a vacuum on the production formation alone, which will increase the production of the formation and which will eliminate the necessity of surface vacuum equipment expensive to install and expensive to maintain. Such a pump will be lubricated by the power oil and will not run hot when the well becomes depleted and the vacuum on the formation may be maintained as long as desired.

While the foregoing is considered a preferred form of the invention, it is by way of illustration only, the broad principle of the invention being deiined by the appended claims.

What I claim is:

1. In a pump for use in a well having a casing and concentric tubing and having an upper and a lower strata fluid conduit, a double wall annular case on the lower end of said tubing, a pump insert in said case, a production tubing in said insert and a power oil tubing in said case and parallel therewith and housed between the walls thereof, an upper swab mand-rel on said production tubing and having swab cups thereon bearing against and sealing said production tubing to said upper swab mandrel, a cylinder tubing mounted on the lower end of said mandrel and check valves in the upper end of said cylinder tubing for admitting production from an upper strata into said cylinder tubing and discharging same from said cylinder tubing, vertically aligned integral reciprocating rods in said cylinder tubing, fluid pressure means for actuation of said rods for compressing and moving fluid in said cylinder, double head pistons mounted adjacent each end of said rods, a pair of power pistons mounted on said rod between said double head pistons, an annular hydraulically adjusted sliding v-alve between said power pistons and hydraulic means having passageways leading from said power oil tubing and a passageway from said production tubing leading into said sliding valve between said power pistons for actuating said sliding valve at the end of each stroke of said rods to reverse the flow of the iiuid pressure means and thus reverse the direction of travel of said rods, check valves in the lower end of said cylinder tubing controlling the dow of production from the lower end of said case into said cylinder tubing, and a lower swab mandrel mounted on the lower end of said cylinder tubing having swab cups thereon bearing against and sealing said production tubing.

2. In a pump for use in a well having an upper and lower production strata and having a casing and concentric tubing, a double wall annular case on the lower end of said tubing, a pump insert in said case, a production tubing in said insert and a power oil tubing in said case and parallel therewith housed between the double walls thereof, an upper swab mandrel on said production tubing and having swab cups thereon bearing against and sealing said production tubing, means for detachably securing said production tubing to said upper swab mandrel, a cylinder tubing mounted on the lower end of said Vmandrel and check valves in the upper 'end of said cylinder tubing Yfor admitting production from an upper strata into said cylinder tubing and discharging same from said cylinder tubing, a reciprocating rod in said cylinder tubing, a flow connection between said power oil tubing and said cylinder tubing, means for applying iiuid under pressure into said cylinder tubing for the actuation of said rod, double head pistons mounted adjacent each end of said rod for compressing and moving the uid into said cylinder, a pair of power pistons mounted between said double head pistons, an annular hydraulically adjusted sliding Valve between said power pistons and ports leading from said power oil tubing into said cylinder means for actuating said sliding valve Iat the end of each stroke of said rod to reverse the direction of flow of fluid pressure and to reverse the direction of travel of said rod, check valves in the lower end of said cylinder tubing controlling the liow of production from the lower end of said case into said cylinder tubing, and a lower swab mandrel mounted on the lower end of said cylinder tubing having swab cups thereon bea-ring against and sealing said product-ion tubing and means in the lower end of said case for aligning said mandrel and cylinder tubing in said case.

3. In a pump for use in a well having a casing and concentric tubing therein, a double wall annular oase mounted on the lower end of said tubing, insert pumping means in said case comprising cylinders having reciproeating rods therein and double headed pump pistons mounted adjacent each end of said rods, conduits in said case housed between said double walls for passage of gaseous fluid and power oil under pressure, and for production iiuids from upper and lower formations, ports in said cylinders in ilow connection with said conduits, valves in said tubing controlling the flow of production fluid through said conduits into and out of the cylinders adjacent each head of said pump pistons and valves in said case for mixing gaseous duid into said production fluid, power pistons on said rods between said pump pistons, an annular hydraulically operated sliding valve between said power pistons controlling the ow of power uid against one head of one of said power pistons, a hydraulically operated valve on said rod for moving said sliding valve at the end of each stroke to block the flow of power iluid against one head of one power piston and permit the exhaust of fluid trapped in the cylinder by said head, and to permit the iow of power iiuid against one head of the other of said power pistons and block the exhaust of fluid trapped by said other head and ports leading from said power oil tubing into said sliding valve.

4. In a pump for use in well bores, a tubular double wall annular case, a pump insert in said case, cylinders in said insert, a reciprocating rod in said cylinders having pump pistons and power pistons thereon, an annular hydraulically adjusted sliding valve in one of said cylinders between said power pistons, power oil inlet lines and power oil exhaust lines leading into said cylinders and housed between the walls of said case, ports in said cylinders in flow connection with the said power, oil lines and said exhaust lines through which the power oil is admitted into and exhausted from the cylinder on each side of said valve and ports leading from said power oil and exhaust lines into said sliding valve, said sliding valve being hydraulically movable to alternate the flow of oil through the exhaust and intake lines, said sliding valve having hydraulically operated seats powered by the power oil exhaust to move said valve into fully seated position at each alternate stroke.

5. In a pump for use in well bores, a well casing, a double wall annular case to be mounted in said casing, a pump insert in said case having gas compressors and production iiuid pumps comprising a reciprocating rod in said insert having double headed power pistons, compression pistons and pump pistons thereon, a plurality of conduits in said case housed between the walls thereof and ports in said pump insert in ow connection with said conduits, a portion of said conduits being provided for passage of production uid and a portion being provided for the passage of gas to `and from said compressors and a portion of said conduits being provided for the passage of power oil therethrough to said pistons, check valves in said conduits controlling the respective ow therethrough, the conduits being arranged in close proximity and being surrounded by uid to provide a cooling action to said compressors and a heating action to said production fluid.

6. In a pump for use in a well, a double wall annular case, ra pump insert in said case having a cylinder therein and a reciprocating rod land production conduits, power pistons, compression pistons and pump pistons on said rod, power oil conduits and gas conduits in said case housed between the walls thereof, ports in said cylinder in connection with said two last named conduits for admission of power oil and gas into said cylinder from said conduits, a sliding valve on said rod for reversing the ow of power oil to power pistons upon the end of each stroke, ports leading into said valve from said power oil conduit, said l valve having hydraulically controlled seating members exposed to the pressure of the exhaust power oil for positively seating said valve at the end of each stroke of the rod.

References Cited in the tile of this patent UNITED STATES PATENTS 1,963,472 Penrod June 19, 1934 2,022,859 Herbsman et al Dec. 3, 1935 2,121,927 P-aul June 28, 1938 2,142,773 Athey Jan. 3, 1939 2,513,869 Hoier July 4, 1950 2,589,672 Coberly Mar. 18, 1952 2,605,712 Davis et al. Aug. 5, 1952 2,780,171 Heddy Feb. 5, 1957 2,822,757 Coberly Feb. 11, 1958 

